to check mine, what we did was get a 'T' fitting.. on one prong we connected the gauge, to one side we connected a short length of fuel hose, and on the other side, we connected the fuel line from the pump to that (you disconnect this from the regulator, and replace it with the short piece of pipe that you just added to the T-piece)
then take it for a drive around the block, under normal driving conditions, and then under boost etc (get someone to come with you to read the gauge) and report back what you find....
from memory (don't quote me on this though, as it's only off the top of my head.... perhaps someone else can help out here) a 'healthy' figure will be around 3 bar (around 45psi) or so?